Basics of LXC: 2 of 2

Posted on Mon 22 August 2016 in LXC

In my previous blog post, I mentioned why I moved from Docker to LXC (reference: here ).

I also mentioned 7 basic commands you will need to get started with LXC. I will list them and walk-through each below.

Container Basics

Let us start by creating and starting a container:

sudo lxc-create -n myfirstcont -t ubuntu
sudo lxc-start -n myfirstcont -d

The first command will create a container called myfirstcont from the remote Ubuntu template.

After the first command has successfully executed, you can start the container using the second command (lxc-start).

Next, we will get into the container:

sudo lxc-attach -n myfirstcont

This command will take you into the container as the root user.

Once you are in the container, you can work with it as you normally would in a regular Ubuntu OS (although a number of regular/standard packages may not be present).

Now that we started our container and we have also managed to get within the container (via lxc-attach), we may need to obtain some information about the container to work with it externally.

A common example is when we start an HTTP-server within the container (and bind the server to the 0.0.0.0 IP). To obtain the IP-address assigned to the container (as well as other basic information), we will use:

sudo lxc-info -n myfirstcont

You will get a basic amount of information using the lxc-info option.

The next 2 commands will stop and destroy your container.

Stopping:

sudo lxc-stop -n myfirstcont

Destroying:

sudo lxc-destroy -n myfirstcont

The container itself will be destroyed, but your template (somewhat similar to a Docker image) will still exist.

The last command is to list all containers on your system. The command will list all containers, regardless of state:

sudo lxc-ls

One important thing to mention about this tutorial is that we are using the default LXC instructions and creating priviledged containers by using sudo. I recommend reading up about the priviledged/unpriviledged aspects of containers here .

Mounting

In my first post, I mentioned that mounting from the host > container or vice-versa took a bit of time to figure out. For the purposes of simplicity and ease-of-use for anyone reading this, here is a set of commands to use for mounting.

Host-to-container:

sudo mount --bind /var/lib/lxc/myfirstcont/rootfs/home/ubuntu/myfolder/ /Project/path/to/hostfolder

Container-to-host:

sudo mount --bind /Project/path/to/hostfolder /var/lib/lxc/myfirstcont/rootfs/home/ubuntu/myfolder

Installing small Python library in a container

If you have not destroyed the container you created above, let us go ahead and restart the container:

sudo lxc-start -n myfirstcont -d
sudo lxc-attach -n myfirstcont

You should be attached as the root-user within the container.

Now run:

apt-get update
apt-get upgrade
apt-get install -y python3-pip
pip3 install pelican markdown

You have now successfully created an LXC container for the static site-generator Pelican .

LXD as an easier LXC-manager

In the final part of this blog post, I would like to mention LXD .

Although the link above explains things better than I can, LXD is a very useful LXC-manager. It provides unpriviledged containers by default and uses the Docker image/container approach (instead of templates).

LXD provides a host of other features that would be useful for large-scale container-management.

I would strongly urge anyone interested in using LXC-containers in production to consider using LXD to manage your infrastructure.